Firing rate reducer



Sept. 18, 1 945. c; w G|| |GAN 2,384,832

FIRING RATE REDUCER Filed April 8, 1944 wwmawgm Patented Sept. 18, 1945 2,384,832 FIRING RATEREDUC'ER" Carl W. Gilligan,'East Longrneadow, Mass.

' iApplication April 8, 1944,"s'eria1 vo. se dom I 5 Claims.

. The invention described herein may be 'manu factured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

"Ihi's invention relates to a firing rate reducer It is an object 'ofrthis invention to provide an improved firing rate' reducer forthe reduction of a normal rate of fire of an automatic firearm.

Another object 'of this invention is' to provide an improved firing rate reducer capable of full automatic or reduced rate of fire by manipulation of the trigger.

The specific nature of the'invent'ion as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:: Fig. 1 is a longitudinal sectional view of a trigger housing embodying this invention wherein the mechanism is shown in the cocked position.

(01.39 m) 7 -(TGrantedunden the act of March 3,. 1883, as:

* amended April 30, 1312s; are vo. c.1757).

. Fig. 2 is a-view similar to Fig. 1 but shown trigger mechanism. A trigger housing of the z type disclosed in U. S; Patent No; 1,293,022 to John M. Browning may be conveniently modified to incorporate this invention and will be-utilized as a specific example to illustrate this invention. In a suitable horizontal recess on the top of housing I there is mounted a sea-r carrier 2. On the extreme right end of carrier 2 there is pivotally mounted a sear 3 as by a transverse pin 4. A carrier spring l5 surrounds a cylindrical end portion l5 of carrier? and is placed between the shoulder formed by such cylindrical end portion of carrier 2 and the end of the recess in housing.

I to cushion the shock resulting from engagement of sear 3 by recoiling members of the firearm as will be later'described; A trigger 5 is pivotally mounted within the hollow interior of housing I by a transverse pin 6 located in the upper left hand portion of housing I as shown in Fig. 1. A disconnector is pivotally mounted on a stud 8 on trigger 5 in such fashion that it will .move upwardly to engage the forward edge 9 10f sear 3:when-trigger 5 is pulled rearwardly.

A sloped surface 31-, ondisconn'ector 1 engages a correspondingly: sloped. surface 38 on carrier-2 when trigger '5- is pulled--rearwardly. Suchsurfaces are provided to cam disconnector 1- ofi the edge 9 of sear 3as.will;be described;

"A split leaf'spring;Ill-is-provided to engage the forward end of sear =3to pivot the rear edge II of sear 3' into the path of an operating slide- |2.

Thus the rear edge 7 H of sear 3 will engage a sear notch |3 provided on'xthe undersideof. slide 12.}: The sear spring 10 also has a downwardly projecting leaf J4 which engages the top surface of 'discon'nector. 1; Leaf 14 .thus holds. disconnec- 't'or-'|j-against the edge-of carrier 2 as shown in Fig. 1 to'insurethat such disconnectorwill always be in position toengage theedge 9 of sear 3,when trigger 5 is pulled rearwardly. A change lever pin 39 having.aslot"4| thereinis mounted iriatrarisverse hole 40 "inhousing-l to permit full a'utomaticor reduced rate 0f'fi1fe"aS7Wi'11 be de- -scribedlater. A lever ('notshown) is provided .on one end of pin 39= onthe outside of the receiver ofthe' firearm to'effect rotation of 'pin' 39 -t0 obtain-the 'fullautomatic' or reduced rate of 'Arr'inertiahammer H is pivotally mounted within the pistol grip portion |8"of housing'l-by 'a transverse pin 19. 1A torsion spring 20 surr'oundspin I9'an'd'is connected to'hammer H in suchffa'shion'that spring-'20 will bias hammer upwardly'into' engagement with a plunger 2|. 'The plunger 2| isinserted in a'verticalhole 22 in housing l as *shown in'-Fig .-1.' Plunger 2| is providedwith a conical-shaped head portion 23 and. fa cylindrical stem portion 24. The conical head portion:23 projects sufficiently above the triggerhousing I s'o'thatplunger' 2| will be struck bythe correspondingly sloped end 42 of; slide -|2 when such slide travels 'rearwardly. Sear3'is'bifurcated to permit head 23 of plunger 2| to pass between such bifurcation and contact slide l2. -A suitable recess 25 is provided on theunderside of slide I2 to accommodate plunger 2| when slide 12 is-in the recoiled position as shown in Fig. 1. A spring 26 surrounds stem portion 24 of plunger 2| andv isplaced within a counterbored portion 21' of hole 22 to bias plunger 2| upwardly against A sear'trip rod 28 is inserted in an upwardly sloped hole- 29in" trigger 5. "A transverse'pi'n 33 provided in'trigger E engagesa slot' '34 on "the edge'of trip rod28'to limi-t thellongitudinal movemerit and prevent-rotationo'f trip rod'281w'ithin trigger 5. Rod '28 projects upwardly thru a suitable hole 36 in carrier 2 to engage the bottom surface of sear 3. The end 30 of trip rod 28 which engages the bottom surface of sear 3 is suitably beveled so as to provide a large engagement area with the bottom of scar 3. The other end of trip rod 28 projects downwardly into pistol grip I8. A surface 3| angularly inclined relative to the axis of the trip rod 28 is provided on the bottom end of rod 28 and a corresponding surface 32 is provided on hammer H. The surfaces 3| and 32 are engaged by movement of the rear end of rod 28 adjacent hammer when trigger is pulled rearwardly. A sloped surface 35 is provided on the upper corner of hammer H as shown in Fig. 1 to strike the end of trip rod 28 as will be presently described.

With the firearm in the cocked position as shown in Fig. 1, that is, with the sear 3 in engagement with sear notch l3 in slide I2, and notch 4| of change lever pin 39 in the position shown, the firearm (not shown) is ready to be 'fired. When trigger 5 is pulled rearwardly, the rear surface of such trigger enters slot 4| of pin 39 and the disconnector 1 is forced upwardly against the end 9 of sear3, forcing the end ll of sear 3 out of engagement with sear notch l3. At the same time trip rod 28 is moved rearwardly so that the end of such rod is opposite sloped surface 35 of hammer N. Slide l2 under the bias of an operating spring (not shown) goes forward to effect discharge of a cartridge in the firearm (not shown) and simultaneously disconnector I slips off the end 9 of sear 3 due to the camming action of sloped surface 31. of disconnector I striking sloped surface 38' of carrier 2. Immediately upon discharge of such cartridge, slide I2 is forced rapidly rearwardly by the automatic mechanism of the firearm and in so doing the end 42 of slide I2 strikes the conical head 23 of plunger 2|" driving the plunger smartly downward. The force of such blow is transmitted to hammer I! by plunger 2| whereupon hammer I1 is rotated in a clockwise direction about pin |9.

In the meantime slide l2 travels rearwardly until it strikes the buffer mechanism of the firearm (not shown). Upon the return travel of slide l2, sear 3 engages sear notch |3 thereby holding slide l2 in the position shown in Fig. 1. The end ll of sear 3 is of course, returned into the path of slide l2 by sear spring II]. It should be appreciated that the time elapsing between slide l2 striking the buffer (not shown) and returning to the point where it again is caught by sear 3, is of extremely short duration.

With slide |2 again engaged by sear 3 the hammer H has about completed its downwardtravel and is about to be returned upwardly by torsion spring 20. As trigger 5 is still held in the rear position for automatic fire, the end of trip rod 28 will then be in the path of hammer I'I when hammer I1 is again returned to the position shown in Fig. 1 by torsion spring 20. Hammer will then strike the end of rod 28, the surface 35 on hammer coming in contact with the end of rod 28. The inertia of hammer drives trip rod 28 forwardly'to raise the forward end 9 of sear 3 which brings the rear end ll of sear 3 out of engagement with sear notch l3 in slide |2. Hence slide 2 moves forwardly to again effect discharge of the firearm, whereupon the cycle will be repeated as long as trigger 5 is held rearwardly."

As the time required for hammer I! to com-- plete its cycle of movement is substantially greater than the time required for slide I2 to travel its cycle from where it strikes plunger2| to the buffing mechanism and return to where it is again held in emagement with sear 3, there is a considerable delay introduced between successive shots and accordingly a substantial reduction in the firing rate.

The normal automatic rate of fire of the firearm is readily obtained by rotating change lever pin 39 by the change lever (not shown) until slot 4| is out of the path of trigger 5. This limits the rearward travel of trigger 5 so that the end of trip rod 28 cannot come into the path of inertia member Thus the rate reducing mechanism is rendered inoperative. The upward movement of disconnector I is likewise limited by restricting the rearward movement of trigger 5. The limited rearward movement of trigger 5 will now permit disconnector to raise only sufiiciently to disengage the rear edge II from sear notch I3. As disconnector stays in contact with sear 3 as long as trigger 5 is held rearwardly the firearm will fire full automatically.

With slot 4| in the position shown in Fig. 1 so that trigger 5 will enter such slot thereby making the rate reducing device operative the firearm can be readily fired fully automatically or at the reduced rate of fire by careful manipulation of the trigger. Pulling the trigger back but a slight amount will permit full automatic fire while pulling the trigger all the way to the rear permits reduced rate of fire.

It is thus apparent that a rate reducing device embodying this invention is of simple, rugged construction and will eifect a substantial reduction in the cyclic rate of the firearm.

I claim:

' 1; In a firearm having a reciprocating slide and a pivoted sear engageable therewith, in combination, a pivoted inertia member, a spring pressed plunger arranged in the recoil path of the slide, cooperating cam surfaces on said slide and said plunger constructed to force said plunger axially by recoil movement of the slide, said inertia member having a portion disposed in the path 01 said plunger whereby a rotational force is imparted to said inertia member, resilient means opposing said rotation, and a disconnecting member having one end engageable by said inertia member during the return movement thereof and the other end arranged to disconnect the sear from the slide by the impact of said inertia member on said disconnector.

2. In a firearm having a reciprocating slide and a pivoted sear engageable therewith, in combination, a pivoted inertia member, means energized by the slide for applying a rotational force to said inertia member, resilient means opposing said rotation, a pivoted trigger, means on said trigger for momentarily pivoting the sear out of slide engaging position bypulling of said trigger, and a plunger slidably mounted in said trigger, one end of said plunger, in the pulled position of said trigger, arranged to be engaged by said inertia member in its return movement, the other end of said plunger arranged to pivot the sear out of slide engaging position by the force received from said' inertia member.

3. In a firearm having a reciprocating slide and a pivoted sear engageable therewith, in combination, a pivoted inertia member, a spring pressed plunger arranged in'the recoil path of the slide, cooperating cam surfaces on said slide and said plunger constructed to force said plunger axially by recoil movement of the slide, said inertia' member having a portion disposed in the path of said plunger whereby a rotational force is imparted to said inertia member, resilient means opposing said rotation, a pivoted trigger, means on said trigger for momentarily pivoting the sear out of slide engaging position by pulling of said trigger, a plunger slidably mounted in said trigger, and one end of said plunger, in the pulled position of said trigger, arranged to :be engaged by said inertia member in its return movement, the other end of said plunger arranged to pivot the sear out of slide engaging position by the force received from said inertia member.

4. The combination defined in claim 2 plus manually operated means for selectively holding said disconnecting member out of engagement with said inertia member.

5. The combination defined in claim 3 plus manually operated means for limiting said move ment of said trigger whereby said plunger is main tained out of engagement with said inertia member.

CARL W. GILLIGAN. 

